Piston



Jan. 27, 19317. H E DEPUTY 1,790,230

' PIsToN Original Filed May 4, 1927 @u 'JW-uro, e?

Patented Jan. 27, 1931 nomen E. DEPUTY, or DETROIT, anoniem FISTOH Application led Iay 4, 1927, Serial No. 188,620. Renewed June 18, 1930.

This invention relates lto pistons and particularly' to pistons for internal combustion engines. In the present practice the majority of pistons for internal combustion engines are formed of cast iron. `hile the relatively light weight of aluminum as compared to cast iron renders the former desirable for piston use, the co-.efrcient of expansion of aluminum is decidedly higher than that of cast iron,

and because of the responsiveness of aluminum to heat change, it is difiicult in utilizing all-'aluminum pistons to avoid an undue looseness and sla ping thereof in their cyli-nders before heating up of the engine, or an undesirably tight fit of. such pistons in the cylinders after heating up. On the other hand, aluminum is more easily and economicall machined than cast iron, and its greater con uctivity of heat, as compared to cast iron is an advantage in dissipating the heat of combustion. Y

l It is the primary'object of the present invention toprovide a piston combining portions of aluminum and cast iron in such a.

manner as to utilize the desirable characteristics of both metals. V

More specifically expressed, the primary object is to form the head and grooved upper portion of a piston of aluminum Ior some slm- I ilar relatively soft metal, and to form the skirt of the piston jointly of an inner aluminum portion integral with said head, and of an embracing sleeve, of cast iron or the like,

more or less embedded in the aluminum mem-v ber andv suitably .bonded thereto.

These and various other objects the invention attains by the constructions hereinafter described and illustrated in the accompanyin drawing, .wherein igure 1 is anaxial sectional view of the piston embodying the improved construction.

Figure 2 is a fragmentary sectional view of the composite skirt portion of the piston.

, Figure 3 is a fragmentary view of an alternative construction.

In these views the reference character I designates the head of a piston, and 2 the relatively thick upper portion of the piston wall, having the usual grooves 3to receive sealing rings, (not shown). 4 and 'designate respectively an aluminum skirt portion of the ypiston formed integrally with the parts '1 and 2 and asleeve of cast iron (or some ment with said sleeve,-and two primary prol visions are made for bonding together the aluminum and cast iron. Thus the sleeve 5 is formed with a plurality of outwardly flaring apertures 7 into which the molten aluminum is iiowed forming heads 8 in said apertures serving to rigidly lock the two metals together. -A second bond is established betweenrthe two metals4 byforming the upper end portion of the sleeve 5 with an annular inturned flange or hook .-9 embedded in the relatively thick upper portion 2pf the piston wall below the grooves of said portion. Said iiange 9 in addition to establishing a bond between the two different 4metals alsa transmits the longitudinal thrust from one to the other of said metals as the piston undergoes its stroke.

A pair of wrist pin bearings 10 are formed either integrally with the sleeve 5,'as shown in Figure 1, projecting oppositely toward each other through the sleeve portion 4, or said hearings may be integrated with the aluminum skirt 4, as shown in Figure 3.

The use of aluminum in the described piston to form the head thereof and the grooved upper portion, andV to also form the inner skirt portion, derives the advantage of 'easy machining and -of rapid heat`conduction that would characterize .an all-aluminum piston. Suicient clearance may be provided without detriment between these portions of the pis ton and the cylinder wall to avoid undue friction. Use of the cast iron sleeve, embrace the aluminum skirt portion of the piston restrains said skirt portion from the undue expansion that would otherwise result from heating of the iston, since the cast iron has a considerably ower co-eiiicient'and will not expand to a detrimental extent whenheated. In forming the described piston, the sleeve 5 before being placed in the' mold in which the aluminum is to be poured ispreferably heated to substantially the temperature of the molten aluminum so as to avoid chilling the latter andpossible resulting imperfections.

The described dual means for bonding the cast iron andV aluminum parts together insures a completely rigid unitary construction and rigidity is further insured by the fact that the relatively high expansive nature of the aluminum portion 4 tends to cause it to bind firmly in the cast iron sleeve when the piston encounters high temperatures in use. Thus it is apparent that the described construction associates in a piston two metals of different hardness so as to utilize the desirable characteristics of both. f

It will be understood to those skilled in the art that the described invention is susceptible of various modifications based upon the dis-I closed principles of construction and the invention is presented therefore as including such changes of its form as fall within the spirit and scope of the appended claims.

What I claim is 1. A piston comprising a metallic skirt portion, an annulus of comparativel hard metal embracing said skirtportion, an a pair of wrist pin bearings integrated with said annulusy and projecting through said skirt portion.l

. 2. A piston comprising a head, a grooved Wall portion, and a skirt portion integrally formed as' a metallic casting, an annulus of relatively hard metal rigidly embracing said skirt portion, and a pair of wrist pin-bearings integrated with said annulus and projecting through said skirt portion. ,v

3. piston comprising a head, a grooved wall portion adjacent to said head, and a relatively thin skirt portion, said head and Wall portlons being integrally formed of metal, of a sleeve embracing said skirt portion formed of a relatively hard metal, formed at its upper end with an annular flange, projecting inwardly and downwardly hooked and embedded in said groove Wall portion, sad` flange, transmitting the end-Wise thrust from one to the other of the specified parts of the pistons.

In testimony whereof, I sign this specication.

HORACE E. DEPUTY. 

